The area of nanoparticles and nanostructures made from nanoparticles has grown over the last few years. Examples of structures made from nano-particles include new batteries and supercapacitors which include a baseline structure made from nanoparticles.
Typically, nanoparticles are formed on a substrate by one or more methods of deposition. For example, physical vapor deposition by sputtering is one such method where a plasma discharge assails a substrate or alike to form a layer of nanoparticles on the substrate. However, these methods of deposition are limited to substrates with planar structures. Therefore, there is a need for forming nanoparticles on substrates that do not have planar structures.
In addition, development of high efficiency and long life thin film solar cell has been ongoing. Copper indium selenium (CIS) and copper indium gallium selenium (CIGS) are semiconductor materials which posses wide band gap range as compared to other semiconductor materials, e.g., silicon. Silicon is the most widely used solar cell material which has a band gap of about 1.1 eV. The optimum band gap for highest efficiency solar cell is about 1.5 eV. Thus, alternative materials such as copper indium gallium selenium (CIGS) have recently attracted more attention. CIGS has a tunable band gap range of between 1.04 eV to 1.67 eV. The band gap of CIGS is manipulated by changing the ratio of indium and gallium. CIGS solar cell with the CIGS film thickness less than 1 micrometer has been demonstrated compared to few micrometer silicon thickness requirements with silicon-based solar cells. The wide band gap ranges lead to high efficiency by converting more energy of incoming photons into electrical energy and producing less thermal dissipation energy.
Additionally, CIS-based solar cells have generally been fabricated by co-evaporation of individual elements. More recently, various cost-effective non-vacuum based fabrication methods of CIS-based solar cells have been developed. Furthermore, CIS and CIGS nanoparticles have been used to develop “ink” which is further utilized to fabricate solar cells by various printing techniques.
These printing techniques provide solar cells on both rigid and flexible substrates. However, printing on a non-planar substrate is both expensive and difficult. In addition, the CIS or CIGS solar cells developed thus far, are not commercially viable for household and other consumer based applications, mostly because of high cost-per-unit-power (i.e., cost of manufacturing per unit energy produced). Therefore, a scalable solution is needed that makes solar cell technology affordable for everyday use.